1. Field of the Invention
This invention relates to a thermoplastic, segmented, linear copolyesterether elastomer having soft segments derived from a poly(alkylene oxide) glycol. More particularly, the invention concerns such an elastomer having poly(1,3-propylenebibenzoate) hard segments.
2. Description of the Prior Art
Various thermoplastic, linear polyetheresters elastomers have been suggested for the production of highly elastic fibers. For example, Greene et al, U.S. Pat. No. 4,906,729 and Greene, U.S. Pat. No. 4,937,314 disclose such elastomers. The elastomers are composed of long chain ester units that constitute the "soft segments" of the elastomer and short chain ester units that constitute the "hard segments" of the elastomer. Generally, the the elastomers are formed of poly(alkylene oxide) soft segments that amount to at least 70 percent of the polyetherester elastomer. U.S. Pat. No. 4,906,729 discloses elastomers with hard segments of poly(ethylene terephthalate) referred to hereinafter as "2G/T", poly(1,4-butylene terephthalate) "4G/T", poly(ethylene-2,6-naphthalenecarboxylate) "2G/2,6N" and poly(1,4-butylene-2,6-naphthalenecarboxylate) "4G/2,6N". U.S. Pat. No. 4,937,314 discloses elastomers with hard segments of poly(1,3-propylene terephthalate) "3G/T". Although the disclosed elastomers are useful for the production of very soft, highly elastic objects, elastomers of less stiffness (i.e., lower initial modulus), higher unload power, and lower set would be particularly desirable for conversion into fibers or films intended for diaper-leg elastification, into hollow tubes intended for vascular prostheses having elastic characteristics approximating those of arterial tissue, or into many other elastic objects. Accordingly, a purpose of this invention is to provide a thermoplastic linear polyetherester elastomer that can be converted into fibers or films or other shaped articles having the above-mentioned desired combination of properties.